EAL

H/A: Dietary Intake (2007)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To evaluate dietary intake and its relationship to lipid parameters in HIV-infected patients with metabolic abnormalities.

Inclusion Criteria:

Cases were HIV-infected patients aged 18 to 60 years, and for patients receiving anti-retroviral therapy, a stable regimen for a minimum of six weeks prior to evaluation was required
Controls were required to have no history of diabetes mellitus.

Exclusion Criteria:

HIV-infected patients with known wasting or evaluated for studies of AIDS wasting were not included in the analysis
Patients were excluded if they had a history of diabetes mellitus; were receiving concurrent therapy with insulin, anti-diabetic agents, glucocorticoids, growth hormone, supraphysiologic testosterone replacement, or anabolic steroids; were current substance abusers; had a major opportunistic infection within the six weeks prior to the study; or were pregnant or breast-feeding within the past year.

Description of Study Protocol:

Recruitment

HIV-infected patients participating in metabolic studies at the Massachusetts General Hospital between 1998 and 2005
HIV-infected patients were recruited from newspaper advertisement, community and referral-based practices; patients could not be directly referred into the study by providers
HIV-negative individuals simultaneously recruited from the community as controls for these studies
HIV-negative controls were recruited using many of the same community newspapers used to recruit HIV-infected individuals.

Design

Case-control study

Blinding used (if applicable)

Not applicable

Intervention (if applicable)

Not applicable

Statistical Analysis

Study had 80% power to detect a difference of 4 grams per day in saturated fat between the HIV and control groups, based on a two-sided T-test, alpha is 0.05 and standard deviation of 15 grams per day
P-values were derived from a mixed effects ANOVA model to determine differences between HIV and control participants adjusting for potential random effects of individual studies into which patients were recruited.

Data Collection Summary:

Timing of Measurements

Cases and controls had been evaluated for metabolic studies between 1998 and 2005
All participants were studied after an overnight fast of 12 hours.

Dependent Variables

Height and weight measured, BMI calculated
Waist and hip circumferences, waist-hip ratio calculated
Body composition measured through dual-energy X-ray absorptiometry and cross-sectional abdominal computed tomography
Resting energy expenditure measured through indirect calorimetry
Blood samples analyzed for complete blood count, CD4 cell count, HIV viral load, and fasting concentrations of glucose, insulin and serum lipid levels.

Independent Variables

Dietary fat intake measured with four-day food records or 24-hour recall
Compared with established 2005 USDA Recommended Dietary Guidelines.

Control Variables

Age
Race
Gender
BMI
Insurance status
Income quartile
Method of dietary assessment
Use of lipid-lowering medications
Protease inhibitor use
Alcohol consumption
Total fiber intake
Impaired glucose tolerance or diabetes.

Description of Actual Data Sample:

Initial N

356 HIV-infected patients (197 men, 159 women), 162 community-derived HIV-negative controls (73 men, 89 women)

Attrition (final N)

As above

Age

Mean age cases is 42±7 years, mean age controls is 41±10 years

Ethnicity

Cases: 56.3% Caucasian, 28.4% African American, 9.9% Hispanic, 5.4% Other
Controls: 61.1% Caucasian, 25.3% African American, 7.4% Hispanic, 6.2% Other

Other Relevant Demographics

Mean duration of HIV illness was 8.5±4.8 years
Mean CD4 count of HIV-infected participants is 444±254 cells/μl
Viral load is 400 (50 to 5,744) copies per ml
88.8% of HIV-infected individuals were receiving anti-retroviral therapy, of whom 66.8% were receiving protease inhibitors and 93.2% were receiving nucleoside reverse transcriptase inhibitors.

Anthropometrics

Other criteria, including age, medication use and reproductive status were similar between the HIV and non-HIV groups.

Location

United States

Summary of Results:

Key Findings

Assessment of dietary intake in this group of HIV-infected patients demonstrated increased intake of total dietary fat (P<0.05), saturated fat (P=0.006), and cholesterol (P=0.006) as well as a greater percentage of calories from saturated fat (P=0.002) and from trans fat (P=0.02), despite similar caloric intake to the control individuals
A significantly higher percentage of HIV-infected patients were above the 2005 USDA Recommended Dietary Guidelines for saturated fat (more than 10% per day, 76.0% of cases vs. 60.9% of controls, P=0.003), and cholesterol (more than 300 mg per day, 49.7% of cases vs. 37.9% of controls, P=0.04)
There were no statistically significant differences in dietary carbohydrate, protein, monounsaturated fat, and polyunsaturated fat intakes between the two groups
Fiber intake (P=0.03) and alcohol consumption (P=0.005) were significantly lower in HIV-infected patients compared to controls
HIV-infected individuals demonstrated higher total cholesterol (P=0.003), higher triglyceride (P<0.0001) and lower HDL (P<0.0001) levels than controls
BMI and waist circumference were not different between HIV-infected and control groups, but hip circumference was lower and waist-hip ratio higher among HIV-infected than control individuals
32% of HIV-infected individuals and 22% of controls met criteria for metabolic syndrome (P=0.02)
Saturated fat intake was strongly associated with triglyceride level [triglyceride level increased 8.7mg/dl (parameter estimate) per gram of increased saturated fat intake, P=0.005] whereas total fat was inversely associated with triglyceride level [triglyceride level decreased 3.0mg/dl (parameter estimate) per gram of increased total fat intake, P=0.02] among HIV-infected individuals
Use of protease inhibitors was not shown to be significantly associated with hypertriglyceridemia among our HIV-infected population.

Author Conclusion:

Increased intake of saturated fat is seen and contributes to hypertriglyceridemia among HIV-infected who have developed metabolic abnormalities. Increased saturated fat intake should be targeted for dietary modification in this population.

Funding Source:

Government:	NIH
University/Hospital:	University of Western Ontario Research Fellowship Fund
Other:	Mary Fisher Clinical AIDS Research and Education Fund

Reviewer Comments:

Dietary intake measured with different methodologies in the metabolic studies. Authors note the following limitations:

Results cannot be generalized to the larger group of HIV-infected patients without metabolic abnormalities nor to HIV-infected patients with wasting or under-nutrition.

Quality Criteria Checklist: Primary Research
Relevance Questions
	1.	Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies)	N/A
	2.	Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about?	Yes
	3.	Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice?	Yes
	4.	Is the intervention or procedure feasible? (NA for some epidemiological studies)	N/A

Validity Questions
1.	Was the research question clearly stated?		Yes
	1.1.	Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified?	Yes
	1.2.	Was (were) the outcome(s) [dependent variable(s)] clearly indicated?	Yes
	1.3.	Were the target population and setting specified?	Yes
2.	Was the selection of study subjects/patients free from bias?		???
	2.1.	Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study?	Yes
	2.2.	Were criteria applied equally to all study groups?	Yes
	2.3.	Were health, demographics, and other characteristics of subjects described?	Yes
	2.4.	Were the subjects/patients a representative sample of the relevant population?	???
3.	Were study groups comparable?		Yes
	3.1.	Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT)	Yes
	3.2.	Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline?	Yes
	3.3.	Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.)	Yes
	3.4.	If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis?	N/A
	3.5.	If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.)	Yes
	3.6.	If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")?	N/A
4.	Was method of handling withdrawals described?		Yes
	4.1.	Were follow-up methods described and the same for all groups?	Yes
	4.2.	Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.)	Yes
	4.3.	Were all enrolled subjects/patients (in the original sample) accounted for?	Yes
	4.4.	Were reasons for withdrawals similar across groups?	N/A
	4.5.	If diagnostic test, was decision to perform reference test not dependent on results of test under study?	N/A
5.	Was blinding used to prevent introduction of bias?		Yes
	5.1.	In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate?	N/A
	5.2.	Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.)	Yes
	5.3.	In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded?	N/A
	5.4.	In case control study, was case definition explicit and case ascertainment not influenced by exposure status?	Yes
	5.5.	In diagnostic study, were test results blinded to patient history and other test results?	N/A
6.	Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described?		Yes
	6.1.	In RCT or other intervention trial, were protocols described for all regimens studied?	N/A
	6.2.	In observational study, were interventions, study settings, and clinicians/provider described?	Yes
	6.3.	Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect?	N/A
	6.4.	Was the amount of exposure and, if relevant, subject/patient compliance measured?	N/A
	6.5.	Were co-interventions (e.g., ancillary treatments, other therapies) described?	N/A
	6.6.	Were extra or unplanned treatments described?	N/A
	6.7.	Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups?	N/A
	6.8.	In diagnostic study, were details of test administration and replication sufficient?	N/A
7.	Were outcomes clearly defined and the measurements valid and reliable?		???
	7.1.	Were primary and secondary endpoints described and relevant to the question?	N/A
	7.2.	Were nutrition measures appropriate to question and outcomes of concern?	Yes
	7.3.	Was the period of follow-up long enough for important outcome(s) to occur?	N/A
	7.4.	Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures?	???
	7.5.	Was the measurement of effect at an appropriate level of precision?	???
	7.6.	Were other factors accounted for (measured) that could affect outcomes?	Yes
	7.7.	Were the measurements conducted consistently across groups?	No
8.	Was the statistical analysis appropriate for the study design and type of outcome indicators?		Yes
	8.1.	Were statistical analyses adequately described and the results reported appropriately?	Yes
	8.2.	Were correct statistical tests used and assumptions of test not violated?	Yes
	8.3.	Were statistics reported with levels of significance and/or confidence intervals?	Yes
	8.4.	Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)?	N/A
	8.5.	Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)?	Yes
	8.6.	Was clinical significance as well as statistical significance reported?	Yes
	8.7.	If negative findings, was a power calculation reported to address type 2 error?	Yes
9.	Are conclusions supported by results with biases and limitations taken into consideration?		Yes
	9.1.	Is there a discussion of findings?	Yes
	9.2.	Are biases and study limitations identified and discussed?	Yes
10.	Is bias due to study's funding or sponsorship unlikely?		Yes
	10.1.	Were sources of funding and investigators' affiliations described?	Yes
	10.2.	Was the study free from apparent conflict of interest?	Yes